Machine for bending tubes.



PATENTE APR. 19,1964.

. Np. 757,593'. v

' G. ff. ATwoon.

MACHINE PoR BBNDING TUBES.

. AYPLIOATION FILED JULY 11, 1902.

2 SHEETS-SHEET 1.

N0 MODEL.

m, w w EN @UN fllfl-.. tlli@ w1 Fm lm v uw www .0 .N. S Y M No. 757,593. PATENTED APB.. 19, 1904.

Y G. F. ATWOOD.

MACHINE FOR BENDING TUBES.

Y 'APPLIUATION FILED JULY 11, 1902.

2 VSHEETS-SHEBT 2.

N0 MODEL.

@ear

.gaby

No. 757,593. j

'v UNITED STATES GEORGE F. ATWOOD, F HOBOKEN,

ILLINOIS.

Y linamaeanprii'19, 1904.

PATE-NT -Ojiriucle.

New ausser, Assienoe lTfo wusr- Y 'nnunnncrnic conn/iur, or cHicAed'ILLi-Nois, lA conrona'rrou or f MACHxNEXFoR BENDING TUBES.

SPECIFICATION forming part of `I ietters Patent No. 757,593, dated April 19, 1904. Y

Appumimmea my 1i, 1962.

To all whom, it may concern):

Io ing tubes, -and has for its object to provide improved mechanism by which a tube maybe bent or twisted smoothly and regularly without wrinkles or distortion.

- The problem of bendinga rectangular tube 5 presents much' greater difficulties than the bending of round tubes, and it has been found that the methods heretofore employed for the Y latter will not attain the desired results lwith rectangular tubing. It is frequently required to bend the rectangular tube on a radius of three or four inches without distortion or wrinkles, and in such a case the outer wall,

and the two edges must stretch a very considerable distance more than `the inner wall.

In attempting to bend a thin rectangulartube by the methods heretofore employed it is y found that before the outer Wall will. stretch the required amount the inner wall will be buckled end distorted. The filling of sand or- `3,0' dinarily used may prevent the metal from bhckling inward, but it will then buckle out ward, which no filling will edectually prevent. IL have invented a new process Vfor bending tubes, which is described in my patent application Serial No. 115,107, filed July 11, 1902,

and which consists, brieiiy, in first subjecting the tube to a longitudinal tensile stress suiii-Uv cient to stretch the metal and then bending the tube While such tensile stress is main tained.

40 Preferably the tube is stretched to approximately the elastic limit of the metal, and this stress is gradually increased as the tube is bent. Ihave found that by this process I can produce a perfectly regular and symmetrical curve or twist without .any appreciable distortion or wrinkle.

The presentinventlon is a machine adapted to manipulate a tube in the manner above institu No. 115,108. (No model.)

arcata, andi win describe the same' in aan by reference to the accompanying drawings, in whichf tion. on line 2 2 of Fig. l. vFig. 3 is an end elevation. Fig. Liis a sectional plan view similar to Fig. 2 but showing the parts in an alternative position. lFig. 5 is adetail Viewshowingter-turn. ing how the tube is plugged at the points where it is clamped, so that it wil-1 `not collapse.

The same letters of reference designate the same parts wherever they are shown.

The rigid framework et, which may be supported'on legs or standards ,has a threaded bearing a" at one end throughl which the longitudinal screw c is passed. The inner end of said screw carries a head or chuck d, which is mounted thereon so that the screw can rotate independently thereof. `A.- removable cross-bar c? is fitted upon pins carried by the chuck Z and lprojects above and belowY the same alongside the horizontal bars of the framework, so that when said cross-bar is in place the chuck cannot rotate, but will merely slide forward or backward as the screw is turned. When the cross-bar is removed, the chuck may be rotated by the aid of a wrench# riphery.l At the other end of the framework the bending-mandrel f, the shaft being so disposed thatl the curve of themandrel will be approximately tangent to a line projected along the longitudinal axis of the screw.

5rIhe head or chuck ci is provided with jaws d' d', which are adapted to grasp one end of the tubing, said jaws being tightened by means of bolts d2 d2. Clamps g g, tightened by bolts g' g', are placed upon the other end of the tubing, and these clamps are seated against lugs f f which projectfrom the top yand bottom of the bending-mandrel. Plugs L i are inserted in the tube at the points where it is clamped to prevent collapse. The tube Figure 1 is a view ofthe machine in el'eva- Fig. 2 is a sectional plan view thereof bar thrust into oneof the holes d in its pe e is mounted a vertical shaft e, which carries K how the tube may be given a twist or quar- Figs. 6 and 7 are detail views showis ralso filled with sand or other filling in accordance with the usual practice.

The' screw c hase long keyway c', along which a pinion is adapted to slide, said pinion being thus thrown into or out of mesh with a spur-gear'lf, as may be desired. The spur-gear cis fixed upon one end of the shaft 7c', the other end whereof carries a worm k2, which engages a worm-wheel r', fixed upon the vertical shaft e' oi' the bending-mandrel. The operation oi' the machine is as follows: A tube of suitable length is plugged and filled with sand and one end clamped between the jaws d Z of the chuck (Z, while the clamps g g, which are placed on the other end, are supported upon the lugs f f of the bending-mandrel, as shown in Figs. 1 and 2. The pinion c is now removed from mesh with the spur-gear ,hand the screw c is turned backward by a crank or other means to put a longitudinal tensile stresson the tube, the mandrel f being held immovable by the wormgear and the head or chuck d being retracted by the screw. When this stress is sulicient to elongate the tube, the pinion c2 is thrown into mesh with the spur-gear l; and the screw c is then turned forward. Now as the screw is rotated the pinion c2 drives the bending mandrel f through' the gearing before described, which is preferably so proportioned that the periphery of the mandrel will move slightly faster than the chuck d, which is ad- Vanced by the screw. By this means not only the initial stress on the tube is kept up, but the stress is gradually increased as the bend is made. Fig. 4c shows th'e position of the man drel in finishing a bend of ninety degrees. The stress upon the tube is so great thatthe inner lwall cannot buckle while the outer wall is stretched, and a perfectly regular and smooth bend is thus secured. v

Ill/Then desired, the tubes may be given a twist, as shown in Fig..5. This may be done by removing the cross-bar z' from the chuck d, so leaving the latter free to turn, and then rotating said chuck through the required arc by means of a wrench-bar thrust into oneof the holes da.

I claim as my invention- 1. In a tu be-bendingmachine, the combination with clamps adapted to unyieldingly hold the tubing, .Of a mandrel and mechanism for moving the clamped tube to bend the same over the mandrel, and mechanism for initially retracting one of said clamps to stretch the tubing, the clamps being' held relativelyr in position to maintain the tubing under a longitudinal tensile stress as thebend is made.

2. In a tube-bending machine, the combination with a rotating mandrel and clamps for holding one end of thevtube, supported by said mandrel, of a screw-c carrying a chuck for holding the other end of the tube, a pinion mounted to rotate .with the screw, a spur-gear meshing with the pinion, and a shaft and wormgear connecting said spur-gear with the rotating mandrel, said spur-gear and pinion being arranged to be thrown into and out of mesh with each other. l y

3. In a machine for bending tubes, the combination with a rotating mandrel and clamps for holding one endof the tube, supported by Said mandrel, of a chuck for holding the other end of the tube, a screw for retracting the chuck to stretch the tube, and gearing arranged to simultaneously rotate the mandrel and advance the chuck, whereby the tube is bent around the mandrel while subjected to a longitudinal tensilestress.

. 4. The combination with the clamps g g adapted to hold one end of the tube to be twisted, of a movable chuck adapted to hold the other end of the tube, and a screw e for retracting the chuck whereby the tube is stretched longitudinally, the chuck being rotatably mounted; whereby the tube may be twisted under a longitudinal tensile stress.

5. In a tube-bending machine, the combina tion with a rotating mandrel carrying a clamp adapted to hold one end of a tube, of a reciprocating chuck for holding the other end of the tube, means for initially retracting the chuck to stretch the tube, and mechanism adapted to rotate the mandrel and advance the chuck while .maintaining the longitudinal strain upon the tube.

In witness whereof I hereunto subscribe my name this 21st day of'May, A. D. 1902.

GEORGE F. ATWOOD. Witnesses:

H. F. WHITE, ARTHUR G. F. LocKwooD. 

